Method for the preparation of stable and reusable biosensing granules

Abstract

The present invention provides a process for the preparation of stable and reusable biosensing granules useful in the assessment of biodegradability of effluents. The biosensing granules are prepared by culturing active aerobic microbial consortia in synthetic medium, separating the active aerobic microbial consortia, immobilizing the microbial consortia using natural polymer to form biosensing granules, and dehydrating the immobilized biosensing granules to obtain stable biosensing granules having a moisture content of 5-30%.

We claim:  
     
       1. A process for preparing stable and reusable biosensing granules useful in assessing biodegradability of an effluent, said process comprises the steps of:
 i. culturing active aerobic microbial consortia in a synthetic growth media, wherein the aerobic microbial consortia is collected from raw sewage, wastewater treatment plants or from activated aerated sludge units, 
 ii. separating the active aerobic microbial consortia from the synthetic media, 
 iii. immobilizing the active microbial consortia using a natural polymer to form immobilized biosensing granules, and 
 iv. dehydrating the immobilized biosensing granules at 24-36° C. for a period of 2 to 20 hours, to obtain stable biosensing granules having a moisture content of 5-30%. 
 
     
     
       2. The process as claimed in  claim 1 , wherein the culturing of the active aerobic microbial consortia comprises the steps of:
 i. inoculating a synthetic growth media with a microbial consortia collected from the group consisting of raw sewage, wastewater treatment plants and from activated aerated sludge units; 
 ii. incubating the inoculated microbial consortia under aerobic conditions at an air flow rate of about 5 ml/minute, at 24° C. to 32° C. for a period of 12-24 hours or until the level of mixed liquor suspended solids (MLSS) reaches 14500-15500 mg/liter on a dry weight basis; and 
 iii. separating the active aerobic microbial consortia by centrifugation for 10-15 minutes and at a temperature of 28° C. 
 
     
     
       3. The process as claimed in  claim 1 , wherein the active aerobic microbial consortia is immobilized using an aqueous natural polymer solution to obtain immobilized biosensing beads, separating the biosensing beads, washing the beads with water, dehydrating the beads at a temperature in the range of 24° C.-32° C. for a period of 4-12 hours to obtain stable biosensing granules having a moisture content of 5-30%; incubating the stable biosensing granules in 2-5% (w/v) aqueous activation solution at 28° C. for 2-10 hours to obtain active stable biosensing granules; and separating the active stable biosensing granules from the activation solution. 
     
     
       4. The process as claimed in  claim 1 , wherein the synthetic growth media consists of, in grams/liter: glucose—30.0; ammonium chloride—6.5; potassium dihydrogen orthophosphate—2.5; dipotassium hydrogen orthophosphate—1.0; sodium bicarbonate—5.5; yeast extract—1.0; urea—0.5; and tryptone—1.0. 
     
     
       5. The process as claimed in  claim 1 , wherein the pH of the synthetic growth media is adjusted to about 7.0 using 0.1 N hydrochloric acid or 0.1 N sodium hydroxide. 
     
     
       6. The process as claimed in  claim 2 , wherein about 10% (w/v) of the microbial consortia is inoculated in the synthetic growth media. 
     
     
       7. The process as claimed in  claim 2 , wherein the inoculated microbial consortia is aerated by passing air at a rate of about 5 ml/minute. 
     
     
       8. The process as claimed in  claim 2 , wherein the growth media is incubated at a temperature of about 28° C. 
     
     
       9. The process as claimed in  claim 2  wherein the growth of the active aerobic microbial consortia is terminated after MLSS reaches 14500-15500 mg/liter. 
     
     
       10. The process as claimed in  claim 1 , wherein the active aerobic microbial consortia is separated from the synthetic growth by a method selected from the group consisting of centrifugation, settling and decanting of obtained supernatant. 
     
     
       11. The process as claimed in  claim 3 , wherein the separated active aerobic microbial consortia is immobilized on a natural polymer using 1-3% (w/v) sodium alginate and 0.2M calcium chloride solution. 
     
     
       12. The process as claimed in  claim 1 , wherein the active aerobic microbial consortia to obtain immobilized biosensing granules is in a range of 3-5% (w/v). 
     
     
       13. The process as claimed in  claim 1 , further comprising incubating the immobilized biosensing granules for 12-24 hours at 4° C. in 0.2M calcium chloride aqueous solution. 
     
     
       14. The process as claimed in  claim 13 , wherein the immobilized biosensing granules are separated from the calcium chloride solution by decanting aqueous liquid. 
     
     
       15. The process as claimed in  claim 1 , further comprising incubating the stable biosensing granules for 2-10 hours in an activation solution comprising 2-5% (w/v) glucose solution, at 24-32° C. to obtain active stable biosensing granules. 
     
     
       16. The process as claimed in  claim 15 , wherein the stable biosensing granules are separated from the activation solution by draining.